Astronomers have found unexpected rings and arcs of ultraviolet light around a selection of galaxies, four of which are shown here as viewed by NASA's and the European Space Agency's Hubble Space Telescope.
Observations from NASA's Galaxy Evolution Explorer (GALEX) picked out 30 elliptical and lens-shaped "early-type" galaxies with puzzlingly strong ultraviolet emissions but no signs of visible star formation. Early-type galaxies, so the scientists' thinking goes, have already made their stars and now lack the cold gas necessary to build new ones.
Hubble images captured the great, shining rings of ultraviolet light, with some ripples stretching 250,000 light-years.
In these Hubble images, ultraviolet light has been rendered in blue, while green and red light from the galaxies is shown in their natural colors.
The study detailing the findings appeared in the April 21 issue of the Astrophysical Journal.
The California Institute of Technology in Pasadena leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory, also in Pasadena, manages the mission and built the science instrument. The mission was developed under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. Researchers sponsored by Yonsei University in South Korea and the Centre National d'Etudes Spatiales (CNES) in France collaborated on this mission.
Graphics and additional information about the Galaxy Evolution Explorer are online at http://www.nasa.gov/galex/ and http://www.galex.caltech.edu.